JPH04368340A - Production of halogenated aromatic compound - Google Patents

Abstract

PURPOSE:To obtain a halogenated aromatic compound having substituent at the para-position in high selectivity while suppressing the formation of by- product such as benzene hexachloride. CONSTITUTION:p-Dihalogenobenzene, 4-halogenotoluene, 4,4'-dihalogeno-diphenyl ether, etc., are produced by halogenating benzene, monohalogenobenzene, toluene, diphenyl ether, etc., in the presence of an L-type zeolite treated with an acid such as hydrochloric acid and nitric acid.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing aromatic halides. More specifically, the present invention provides a method for selectively producing an aromatic halide having a substituent at the para position.

0002

BACKGROUND OF THE INVENTION Aromatic halides are industrially important compounds as solvents, raw materials for pharmaceutical and agricultural intermediates, and raw materials for engineering plastics. In particular, paradichlorobenzene (hereinafter abbreviated as PDCB) is one of the engineering plastics, polyphenylsulfone (hereinafter referred to as PP).
With the rapid growth in demand for PPS, its importance is increasing.

It is known that PDCB can be obtained by liquid phase chlorination of benzene using L-type zeolite as a catalyst (
(Japanese Unexamined Patent Publication No. 163329/1983). According to this method, paradichlorobenzene can be obtained with high selectivity.

However, when this L-type zeolite is used as a catalyst, the by-product of harmful chlorine adducts (hereinafter abbreviated as BHCs) such as benzene hexachloride cannot be avoided. This BHC by-product not only reduces the yield of the target product but also causes catalyst deactivation. The present inventors actually investigated the effect of BHCs on the catalytic activity and found that when monochlorobenzene containing 0.3 mol% of BHCs was used for chlorination, monochlorobenzene containing no BHCs The catalytic activity was reduced to about 1/4 compared to when using . Therefore, suppressing the production of BHCs is very important when carrying out a chlorination reaction on an industrial scale using an L-type zeolite catalyst.

[0005]

[Problems to be Solved by the Invention] In this way, L-type zeolite can be used as a catalyst for halogenating aromatic compounds.
Although it has the excellent feature of selectively producing para-substituted products with relatively high activity, it has the drawback of producing BHCs as a by-product. Therefore, there has been a strong desire for a catalyst that has activity and para-substituted selectivity equivalent to that of L-type zeolite, and that generates extremely few BHCs.

[0006]

[Means for Solving the Problems] The present inventors have conducted extensive research in order to solve the above technical problems. As a result, L
The present inventors have discovered that when L-type zeolite is treated with acid, the production of BHCs can be suppressed while maintaining the original activity and para-substituted selectivity of L-type zeolite, leading to the proposal of the present invention.

That is, the present invention provides the following formula:

[0008]

[Chemical formula 3]

(However, R1 is a hydrogen atom, a halogen atom, an alkyl group, or a phenoxy group.) The following method is characterized in that the compound represented by the following formula is halogenated in the presence of L-type zeolite brought into contact with an acid. formula

0010

[C4]

(However, R2 is a halogen atom, an alkyl group or a 4-halogenophenoxy group, and R3 is a halogen atom.)

The raw material used in the present invention is a compound represented by the above formula (I). The alkyl group in the formula (I) is not particularly limited, but when the alkyl group is bulky,
An alkyl group having 1 to 3 carbon atoms is preferred because the raw material will not enter the pores of the L-type zeolite used as a catalyst, resulting in a decrease in activity and paraselectivity.

Specific examples of raw materials used in the present invention include benzene, monofluorobenzene, monochlorobenzene, monobromobenzene, monoiodobenzene, toluene, and diphenyl ether.

In the present invention, any known L-type zeolite can be used without any restriction. L-type zeolite generally has the following formula aM2/n O.Al2O3.bSiO2 (where M is an alkali metal or alkaline earth metal, n is the valence of M, and a is 0.7 to 1.7. , b is a number from 4 to 8), and is 11.8 at 2θ in X-ray diffraction.
This compound has peaks around 14.8°, 22.7°, and 28.0°. M in the above formula is usually potassium, but it can be replaced by other metals such as sodium, rubidium, cesium, magnesium, calcium, strontium, barium, etc. by ion exchange. The L-type zeolite in the present invention may be ion-exchanged with a metal other than potassium, and may be ion-exchanged with a metal other than potassium.
It may be ion-exchanged with more than one type of metal.

[0015] The L-type zeolite used in the present invention must be one that has been brought into contact with an acid. As the acid, both inorganic acids and organic acids can be used. Specific examples of acids that can be suitably used in the present invention include inorganic acids such as hydrochloric acid, nitric acid, hydrofluoric acid, sulfuric acid, phosphoric acid and chloric acid; and organic acids such as formic acid and acetic acid.

[0016] The method of contacting the L-type zeolite with an acid is not particularly limited, but a method of immersing the L-type zeolite in an acid is preferred. The pH of the acid is not particularly limited as long as it is less than 7.0, but if the pH is less than 1, the structure of L-type zeolite may be destroyed depending on the contact method, and if the pH exceeds 5. It is preferable to use an acid with a pH of 1 or more and 5 or less because the effect of contact with the acid is less likely to appear. For this reason, it is generally preferable to use the acid diluted with a solvent. As the above solvent, water, alcohol or a mixture thereof is used.

[0017] When catalyzing L-type zeolite with the acid, the ratio of the amount of L-type zeolite to the acid, temperature, and time vary depending on the pH of the acid used or the contact method, and it is difficult to unambiguously define the contact conditions. It is. Generally, these contact conditions are not particularly limited as long as they do not essentially destroy the basic structure of the L-type zeolite. For example, the ratio of L-type zeolite to acid is generally 1 m based on the unit weight of zeolite.
l to 10 l/g of zeolite, more preferably 1
Selected from the range of 0 to 500 ml/g of zeolite. Also, the temperature at this time is generally 0 to 100°C,
More preferably, the temperature is selected from the range of 10 to 70°C. Further, the immersion time is generally 1 minute to 24 hours, but is more preferably selected from the range of 10 minutes to 10 hours. After being brought into contact with an acid, the L-type zeolite is separated from the acid by filtration or the like, and then dried at 80 to 500°C for 1 to 24 hours either as is or after washing with the solvent used to dilute the acid.

The L-type zeolite thus brought into contact with an acid can be used alone or in combination with different types of zeolites. Furthermore, the L-type zeolite that has been brought into contact with the above-mentioned acid can be further treated as described below, unless the basic structure of the L-type zeolite is destroyed. Examples of the treatment method include ion exchange, modification with salts of alkali metals, alkaline earth metals, rare earth metals, or other metals, alkali treatment, heating, treatment, and the like. Further, it can be used together with additives as long as they do not significantly reduce the catalytic activity or the selectivity of the para-substituted product. Examples of additives that can be used include: organic phosphorus compounds such as trialkylphosphines; aromatic amines such as quinoline and pyridine; quaternary ammonium halides such as benzyltrimethylammonium chloride, and sulfur-containing compounds such as halogenated sulfur. It is.

Further, the shape of the L-type zeolite brought into contact with these acids is not particularly limited, and any shape such as powder or pellet can be used. Moreover, it can also be molded using a binder such as alumina, silica, or silica-alumina. Generally, from the viewpoint of ease of handling, it is preferable to use a binder and form it into a pellet. At this time, the order of contacting the L-type zeolite with the acid and molding is not particularly limited, and it is also possible to use the L-type zeolite molded with a binder or the like in contact with the acid.

In the present invention, a halogenating agent is used to halogenate the raw material. Known halogenating agents can be used without any limitations, but generally,
Halogen molecules such as fluorine, chlorine, bromine, and iodine are commonly used. Although the halogenation reaction can be carried out without distinction between liquid phase and gas phase, it is preferable to use the liquid phase method since the reaction temperature is generally high in the gas phase method and high halides are likely to be produced. When halogenating by a liquid phase method, the raw materials can be used as they are, or they can be diluted with a solvent. The solvent that can be used at this time is not particularly limited, but examples of those that can be suitably used include carbon tetrachloride, chloroform, and Freon 113.
Examples include halogen-containing hydrocarbons such as. Generally, it is preferable to carry out the reaction without a solvent in consideration of separation of the product after the reaction is completed.

[0021] The reaction can be carried out using a flow method, a batch method or a semi-batch method, but in consideration of productivity and operability, a flow method is preferable. When carrying out a flow reaction, the raw materials and halogenating agent are placed in a reactor with a fixed catalyst, or the halogenating agent is diluted with an inert gas such as nitrogen when the halogenating agent is a gas. When it is a liquid, it is common to dilute it with the solvent and supply it continuously.

The material of the reactor is not particularly limited, but when using a material containing a substance such as iron that reacts with a halogenating agent to produce a Lewis acid, a material such as resin lining, gas lining or plating may be used. Preferably, these materials are treated so that they do not come into contact with halogenating agents. This is because Lewis acid catalysts generally have higher activity than zeolite catalysts, and the presence of even a trace amount of Lewis acid in the reaction system impairs the para-substituted selectivity, which is a characteristic of L-type zeolite. Furthermore, when a light-transmitting substance such as glass is used as the material of the reactor, it is preferable to shield it from light in order to avoid the production of BHCs due to photoreaction.

[0023] The reaction temperature may be in the range of not less than the melting point of the raw materials under the reaction pressure and not more than the decomposition temperature, but in consideration of reaction efficiency and the like, a range of 30 to 200°C is preferable. The reaction can be carried out under increased pressure, normal pressure or reduced pressure, but in view of the simplicity of the apparatus, it is preferable to carry out the reaction under normal pressure or slightly increased pressure.

The amount of catalyst used in the reaction varies depending on the size of the reactor, the feed rate of raw materials, the amount of binder used during catalyst molding, molding conditions, etc. 0.01 to 20 expressed in zeolite weight
00 g/l, more preferably in the range of 0.1 to 1000 g/l. Further, the feed rate of the raw material varies depending on the size of the reactor, but it may be selected from a rate such that the residence time thereof is in the range of 0.1 to 100 hours. Regarding the halogenating agent, if the halogenating agent is a liquid, the speed is such that the residence time is in the range of 0.1 to 100 hours, and if the halogenating agent is a gas, Gas supply rate per unit reactor volume is 0.01~1l gas/min・l-
The speed can be selected from the range of the reactor volume.

[0025] Furthermore, the supply amount ratio of the raw material and the halogenating agent is expressed as the ratio of the number of moles supplied per unit time.
The halogenating agent may be selected from the range of 1:0.001 to 1:10, but considering the raw material utilization rate, the range of raw material:halogenating agent = 1:0.01 to 1:2 is preferable. be.

The aromatic halide obtained by the halogenation reaction is obtained as a mixture with unreacted raw materials. Aromatic halides having a substituent at the para position can generally be separated by distillation, crystallization, or other operations after the reaction.

By the method described above, the following formula (II)

[0028]

[C5]

An aromatic halide represented by the formula (R2 is a halogen atom, an alkyl group or a 4-halogenophenoxy group, and R3 is a halogen atom) is obtained.

When a compound in which R1 in the above general formula (I) is a hydrogen atom or a halogen atom is used as a raw material, an aromatic halide in which R2 in the above general formula (II) is a halogen atom is obtained. It will be done. In addition, the general formula (
When a compound in which R1 in I) is an alkyl group or a phenoxy group is used as a raw material, R2 in general formula (II)
are each an alkyl group or a 4-halogenophenoxy group.

[0031]

[Effect of the invention] The L-type zeolite used in the present invention when brought into contact with the acid acts as a catalyst in the halogenation reaction,
Aromatic halides with a substituent at the para position are produced with high selectivity. At this time, as is clear from the examples described later, the production of BHCs, which are catalyst poisons, which were unavoidable as by-products in conventional L-type zeolites, is greatly suppressed. These results demonstrate that the present invention can be highly evaluated as an industrial technology for producing aromatic halides having para-substituted compounds.

[0032]

[Example] To explain the present invention more specifically, the following
Although the present invention will be described with reference to Examples and Comparative Examples, the present invention is not limited to these Examples.

Example 1 2.0 g of L-type zeolite (trade name HSZ-500KOA, manufactured by Tosoh Corporation) was added to 100 cc of an aqueous solution of hydrochloric acid at pH 2.
After stirring at room temperature for 1 hour, the mixture was separated. The same operation was repeated twice using the filtered L-type zeolite. Finally, it was washed with ion-exchanged water, filtered, and dried at 110°C for 3 hours and at 400°C for 2 hours.

[0034] The above L-type zeolite 0.0 was placed in contact with an acid in a brown glass four-necked flask with an internal volume of 300 cc.
5 g and 250 cc of monochlorobenzene (hereinafter abbreviated as MCB) with a moisture content of 5 ppm, which had been dried with a molecular sieve and filtered through a 0.5 μ filter, were introduced, and a stirring device, a chlorine blowing nozzle, a reflux device, and a thermometer were connected. In order to avoid a radical chlorine addition reaction to the aromatic ring due to light, the reactor, reflux vessel, and chlorine introduction line were completely covered with aluminum foil and then heated to 110°C. After the temperature inside the reactor stabilized, 75Nc of chlorine gas was added.
The reaction was carried out by blowing at a flow rate of c/min. A portion of the reaction solution was sampled 3 hours after the start of the reaction, immediately treated with a 0.5N aqueous sodium hydroxide solution, and analyzed for organic components by gas chromatography. As a result, the addition rate of MCB was 11.
2%, PDCB and BHC based on the input MCB
The production rate of BHCs is 9.7 mol%, respectively, and 0.04% of BHCs.
It was mol%. Note that the selectivity of PDCB in the product at this time was 86.6%.

Examples 2 to 6 L-type zeolite was brought into contact with an acid in the same manner as in Example 1, except that the type of acid used in Example 1, the pH, and the number of treatments were changed as shown in Table 1. .

Further, reactions and analyzes were carried out in the same manner as in Example 1 using L-type zeolite brought into contact with these acids. The results are also shown in Table 1.

[0037]

[Table 1]

Comparative Example 1 L-type zeolite (trade name: HSZ-500KOA, manufactured by Tosoh Corporation) that was not brought into contact with acid in Example 1
The reaction and analysis were carried out in the same manner except that . As a result, the conversion rate of MCB was 10.1%, the selectivity of PDCB was 88.1%, and the production rate of BHCs was 0.28%.

Example 7 L-type zeolite 0.6 was brought into contact with the same acid used in Example 1 in a brown four-necked flask with an internal volume of 50 cc.
25 g and 17.0 g of diphenyl ether were added. After connecting a stirrer, a blowing nozzle, a reflux device, and a thermometer, the mixture was heated to 80° C. while blowing nitrogen gas. After that, switch the nitrogen gas to chlorine gas, and change the chlorine gas to 37Nc.
The blowing reaction was carried out at a flow rate of c/min. After 13 hours, a portion of the reaction solution was collected and analyzed by gas chromatography, and the conversion rate of diphenyl ether was 100%.
The selectivity of 4'-dichlorophenyl ether is 79.8%
, the production rate of BHCs was 0.35%.

Comparative Example 2 Reaction and analysis were carried out in the same manner as in Example 7 except that L-type zeolite which was not brought into contact with acid was used. As a result, the conversion rate of diphenyl ether was 1
00%, the selectivity of 4,4'-dichlorodiphenyl ether was 79.6%, and the production rate of BHCs was 2.9%.

Reference Example An MCB solution containing 3.1 mol % of BHCs was prepared by blowing chlorine gas into MCB with a water content of 5 ppm without a catalyst under light irradiation.

[0042] L-type zeolite (trade name HSZ-5) dried at 400°C was placed in a brown four-neck flask with an internal volume of 300 cc.
0.05 g of MCB (manufactured by Tosoh Corporation) and 225 cc of MCB with a water content of 5 ppm were introduced. After contacting the stirrer, chlorine blowing nozzle, and reflux thermometer, the mixture was further shielded from light with aluminum foil and heated to 110°C. Solution temperature is 110℃
When this amount was reached, 25 cc of the previously prepared MCB containing 3.1 mol % of BHCs was added using a dropping funnel over about 10 minutes. The reason why it was added at 110°C is that BHCs may be irreversibly adsorbed to L-type zeolite if added at a low temperature. After the addition was completed, the mixture was allowed to stand overnight at 110° C. with stirring, and then chlorine gas was blown into the mixture at a flow rate of 75 Ncc/min. When a portion of the 3-hour reaction solution was sampled and analyzed by gas chromatography, the MCB conversion rate was only 2.6%, and P
DCB selectivity is 88.2%, BHC concentration is 0.42
It was mol%.

Example 8 In a brown four-necked flask with an internal volume of 200 cc, 5 g of L-type zeolite was brought into contact with the same acid used in Example 1.
, 92.1 g of toluene was added. After connecting a stirrer, a blowing nozzle, a reflux device, and a thermometer, the mixture was heated to 70° C. while blowing nitrogen gas. Thereafter, the nitrogen gas was switched to chlorine gas, and the chlorine gas was blown at a flow rate of 110 Ncc/min to carry out a reaction. After 4 hours, a portion of the reaction solution was collected,
When analyzed by gas chromatography, the reaction rate of toluene was 98.1%, and the selectivity of 4-chlorotoluene was 6.
The production rate of BHCs was 0.06%.

Comparative Example 3 Reaction and analysis were carried out in the same manner as in Example 8 except that L-type zeolite which was not brought into contact with acid was used. As a result, the conversion rate of toluene was 97.9%.
The selectivity of 4-chlorotoluene was 66.5%, and the production rate of BHCs was 0.33%.

Claims (1)

[Claims] Claim 1: A compound represented by the following formula [Formula 1] (wherein R1 is a hydrogen atom, a halogen atom, an alkyl group, or a phenoxy group) is mixed with a halogen compound in the presence of L-type zeolite that has been brought into contact with an acid. A method for producing an aromatic halide represented by the following formula [Chemical formula 2] (wherein, R2 is a halogen atom, an alkyl group, or a 4-halogenophenoxy group, and R3 is a halogen atom). .